The present invention relates to pipes for carrying water and the like and, in particular, it concerns methods for connecting pipes and the corresponding pipe elements and connections.
Various techniques are known for connecting water pipes in fire prevention and domestic water supply systems. For many years, the only alternative to threading or flange connections was a labor intensive welding processes. More recently, a number of quickassembly systems have been marketed. These systems seek to reduce the labor costs of assembly by providing various types of mechanical engagement to hold pipe ends together without requiring welding.
One quick-assembly system of particular interest is disclosed in U.S. Pat. No. 5,040,831 and is available commercially in the U.S. under the tradename POZ-LOK.RTM. from Southwestern Pipe, Inc. This system employs specially molded connector fittings which have slots on opposite sides. A pipe is inserted into the connector and a U-shaped bracket is hammered in through the slots. The bracket creates indents in the sides of the pipe, thereby retaining the pipe within the connector.
The POZ-LOK.RTM. system has at least two major advantages. Firstly, it is extremely quick and simple to assemble, requiring only a hammer to drive in the brackets. And secondly, the system readily allows disassembly and subsequent reassembly without compromising the joint structure. However, the system is still far from ideal. Precise alignment of the brackets during assembly is ensured by providing a heavy specially produced molded connector. The manufacturing cost of these connectors offsets to a large extent the cost advantages of labor savings. This is true even for iron piping. In the case of the increasingly popular copper piping, the manufacturing costs of such bulky connectors would be unacceptably high.
In order to produce a quickfit system with lower production costs, a number of systems use thin walled connectors which can readily be produced from modified sections of standard piping. An example of such a system is commercially available in the U.S. under the tradename PRESSFIT.TM. from VICTAULIC.RTM..
The PRESSFIT.TM. system employs a thin walled connector with an internal O-ring seal positioned around the end of a pipe. Engagement of the pipe within the connector is achieved using a special hydraulic circumferential press tool which makes a circumferential indent around the joint through both the connector and the pipe, thereby permanently fixing them together.
The PRESSFIT.TM. system also suffers from a number of disadvantages. Firstly, assembly requires use of an expensive specialized tool which is also very heavy and awkward to handle. Furthermore, the jaws of the tool itself are specific to a given diameter of pipe such that considerable time and labor is required to switch the jaws each time a different gauge of pipe is encountered. Additionally, the joints produced are permanent and can only be dissembled by cutting out and replacing a section of pipe. This renders maintenance and service costs high.
There is therefore a need for a quickfit method for connecting pipes which does not require heavy molded fittings or specialized tools, and which can be non-destructively dissembled for servicing. It would also be advantageous to provide pipe elements and connections corresponding to such methods.